Lamp



May 1, 1934. sPERTl 1,956,598

LAMP

Original Filed Jan. 15, 1932 Patented May 1, 1934 PATENT OFFICE LAMP George Spcrti, Covington, Ky., assignor to Sperti Lamp Corporation, New York, N. Y., a corporation of Delaware Application January 15, 1932, Serial No. 586,851 Renewed July 12, 1933 12 Claims.

This invention relates to are electrodes for use in lamps of the type combining a source of visible radiation and an arc constituting a source of ultra-violet radiation, or for use in any arc lamp.

In the prior application of George Sperti, Serial No. 572,394, filed October 31, 1931, there is disclosed a lamp embodying an outer bulb containing the usual or any suitable incandescent filament which provides a source of visible radiation and an inner bulb in which an arc is established to provide a source of ultra-violet radiation. The resultant spectrum of such a lamp is that of an incandescent filament such as tungsten having superimposed thereon the radiation of an arc in some ionized gas or vapor, for example, the mercury are which is rich in the blue end of the visible spectrum and also in the short wave region of the ultra-violet spectrum that is valuable for therapeutic purposes. By separately enclosing the incandescent filament and the arc, the two sources are rendered independent of one another and can be operated under optimum conditions, so that the lamp can be operated at normal house lighting voltages and currents as in the case of the ordinary incandescent lamp. With such uses in view, the lamp is entirely self-contained and the arc is self-starting without the use of devices external to the lamp.

The present invention relates primarily to the ultra-violet arc element of a lamp of this type. As described in the aforesaid application, the arc is established between spaced electrodes in an atmosphere of ionized gas such as neon, ar-

- gon, etc., or of ionized vapor such as mercury,

or of both, and in order to render it self-starting, the electrodes are preferably heated by filaments connected in the lamp circuit and also connected across the electrodes so as to provide a suitable potential drop therebetween. Due to the heat given off by the filaments, together with the use of oxides such as zirconium, strontium and barium in the electrodes, the gas or vapor in the arc chamber quickly ionizes and the arc strikes between the electrodes. This arrangement has heretofore required in the arc chamber separate spaced electrodes, a heating filament for each electrode, and the necessary separate supports for the individual electrodes and connections from the several filaments to external sources of supply. Such arrangements take up considerable space and require careful attention during assembly to the location and spacing of the electrodes. Moreover, it has been necessary in some cases to introduce separate conductors into the sealed arc chamber in order to supply each filament and to provide separate supports for the separate electrodes. Still further, it is desirable that all hot wires and filaments within the arc chamber be enclosed to prevent the arc strik- 6 ing to them, and this has heretofore been diflicult to accomplish.

One of the objects of the present invention is to provide a unitary electrode element carrying a pair of electrodes in spaced and insulated relation for establishing and maintaining an arc whereby the electrodes may be manufactured and installed as a single unit and mounted by a common supporting means.

Another object is to provide a unitary electrode element embodying spaced electrodes and heating filaments therefor so arranged that only two conneotions are required to a source external to the arc chamber.

A further object is to provide an electrode element for the purposes described which is small and compact, easily manufactured and installed, and adapted for quantity production.

A still further object is to provide an electrode element which can be manufactured and installed as a unit with the electrodes in definitely, located positions so that attention during assembly to the location and spacing of the individual electrodes is unnecessary.

Another object is to provide an electrode element wherein the heating filaments for the electrodes and the connecting wires are substantially all enclosed within the element so as to eliminate any danger of the are striking to the filaments or wires.

One embodiment of the invention has been illustrated in the accompanying drawing, but it is to be expressly understood that said drawing is for purposes of illustration only and is not to be construed as a definition of the limits of the invention, reference being had to the appended claims for this purpose.

In the drawing,

Fig. 1 is a perspective view of a complete lamp embodying the invention, and

Fig. 2 is a sectional view of the ultra-violet producing element.

Referring now to Fig. 1, the lamp shown by way. of example embodies a bulb 1 provided with a base 2 which as shown is of the usual screw type. Sealed in the neck of the bulb 1 is a stem or standard 3 constituting the usual support for the elements within the lamp and also the usual means for introducing the necessary conductors therein. As shown, a wire 4 connected to the shell of the lamp base and a wire 5 connected to the usual contact member of the lamp base provide means for supplying current to the lamp.

An incandescent filament 6, preferably of tungsten, is supported in the lamp by means of supporting wires '7 and 8 that are fused in the'stem 3, wire 'I being connected as shown in Fig. 2 with wire 4 in order to supply current to the filament. The filament may also be supported by a plurality of wires 9 secured to a head 10 on the ultravlolet producing element. It will thus be observed that the incandescent filament is mounted and supported within the lamp in accordance with the usual practice in making incandescent lamps, the ultra-violet producing element and the head 10 forming the counterpart of the usual glass supporting rod. The elements thus far described constitute no part per se of the invention and are shown only for purposes of illustration. a

The ultra-violet producing element is shown in detail in Fig. 2. A bulb 11, on which the bead 10 is formed, is mounted on the stem 3 in any suitable manner as by means of a band 12 and supports 13 and 14 welded or otherwise secured to said band and fused in the stem 3. A stem 15 is sealed in the neck of the bulb 11 after the same is evacuated and partially filled with a quantity of suitable'gas or vapor, said stem 15 constituting a means for mounting the electrode element within the bulb and for introducing the necessary conductors into the are chamber. In the form shown, a wire 16 leads from one end of the filament 6 through the stem 15 into the arc chamber while the other lead is constituted by a wire 1'7 and a support 18 which are connected through the support 13 with the wire 5.

Within the arc chamber is an electrode element 19 of suitable insulating material such as magnesium oxide which is supported in any suitable manner as by means of a band 20 to which one or more of the supports 18 are welded or otherwise suitably secured, said supports being fused in the base 15. The electrode element 19 carries a pair of spaced electrodes and houses heating filaments therefor, all of which are assembled and connected before the element 19 and stem 15 are sealed in the bulb 11. In the form shown, these electrodes are constituted by spaced sleeves 21 and 22 at opposite ends of the element 19, said sleeves being of tungsten or other metal, zirconium oxide, or any other suitable material which is a conductor and which does not evaporate substantially during operation of the arc. The sleeves 21 and 22 may be secured to the element 19 in any suitable manner and in the form shown said element is reduced in diameter at 23 and the sleeves 21 and 22 are crimped or rolled over the shoulders 24 and 25. Preferably, the electrode sleeves are likewise provided with a coating of suitable oxides indicated graphically at 26 and 27. These oxides may comprise thorium, barium, strontium, etc., which on being heated assist in starting the arc, and where the electrodes are of zirconium oxide and the like may be mixed with the electrode material. After the arc strikes, it tends to concentrate on the adjacent ends of the electrode sleeves 21 and 22 and hence the oxide coatings 26 and 27 are preferably placed on the outer remote ends of these electrode sleeves so that they are not used up during continued arc operation.

The current is supplied to the electrodes in any suitable manner, andit will be understood that the particular circuit now to be described is capable of considerable variation and is shown to illustrate the use of the electrode element constituting the invention. In the form shown, a wire 28 connects the electrode sleeve 22 with the wire 16, while the electrode sleeve 21 is connected with a support 18 by a wire 29 passing through a passage 30 in the electrode element. The wire 29 may include a resistance 31 which is in series with the arc and acts as a ballast. The heating filaments for the electrode sleeves are enclosed in passages 32 and 33 formed in the electrode element, and are connected in series with each other and across the electrodes so as to provide a potential drop therebetween. As shown, wire 16 is connected with filaments 34 and 35 positioned in the passage 32 adjacent the electrode sleeves 22 and 21, respectively, and the filament 35 is connected by a wire 36 with filaments 37 and 38 positioned in the passage 33 adjacent the electrode sleeves 21 and 22, respectively. The circuit is completed by a connection 39 from the filament 38 to the support 18. It will be understood that the number and arrangement of the passages in the electrode element may vary depending on the requirement of the particular circuit used.

When current is supplied to the lamp, as by screwing it into the usual lamp socket and turning on the switch, it passes through a series circuit in the lamp including wires 4 and 7, filament 6, wire 16, filaments 34, 35, 37 and 38, support 18, wire 17, support 13 and wire 5. The filament 6 heats up to incandescence, providing a source of visible radiation, The filaments 34, 35, 37 and 38 heat the electrode sleeves 21 and 22 and their oxide coatings 26 and 27. The gas or vapor within the arc chamber becomes ionized due to the heat from the various filaments, electronic emission from the oxide coatings, and emission of vapor ions adsorbed by the walls of the arc chamber and by the electrodes, and the are strikes between the ends of the electrode element and then establishes and maintains itself between the adjacent ends of the sleeves 21 and 22. The characteristics of the arc will depend upon factors such as the temperature of the electrodes, the gas or vapor pressure -in the arc chamber, and the voltage applied to the electrodes, and these factors may be regulated so as to givea concentrated intense are between the electrode sleeves or a glow which substantially fills the arc chamber. Where mercury 1 vapor, with or without gas such as neon, is employed within the arc chamber, the vapor pressure at the operating temperature of the lamp should preferably be low. Vapor pressures as low as 10 to 30 millimeters of mercury are suitable, 1 although the pressure may be either less or greater than these pressures. Under such conditions, the arc will strike quickly at voltages across the electrodes as low as 10 and 20 volts and the filaments 34, 35, 37 and 38 may be designed to produce the desired striking voltage. As soon as the arc strikes, most of the current flows through the arc path and little energy is dissipated in these heating filaments.

For arc operation, the filament 6 and the re- 1 sistance 31 are in series with the arc current and act as ballasts. The resistance 31 may not be necessary. However, it will be desirable in some cases to prevent an excessive increase of current through the filament 6 when the arc strikes which 1 might burn out the filament as disclosed and claimed in a copending application Serial No. 586,852, filed January 15, 1932. The proportions of energy dissipated during operation of the lamp in the filament 6 and in the arc may vary consid- 1 erably. For example, in a seventy-five watt lamp ten to twenty watts may be dissipated in the arc and the remainder in the incandescent filament,

ordinary incandescent lamp contains radiation as short as 3000 to 3100 Angstrom units, but in the usual lamp these short waves are absorbed by the glass bulb. Therefore lamps designed to produce therapeutic effects generally employ special ultraviolet transmitting glass for the bulb, such as that known as Corex. The material of both the outer and inner bulbs of the present lamp may accordingly be of such ultra-violet transmitting glass in order that the short wave length ultra-violet energy maybe emitted and the arc spectrum superimposed on the spectrum of the incandescent filament. Where mercury and other materials are used in the are which also emit the undesirable short wave lengths, the radiation from the are should be filtered in any suitable manner. Thus the bulb 11 may be of material having the desired filtering characteristics, or a filter shield 40 is positioned within the arc chamber which may be of material such as mica as described in the prior application referred to above.

It will be seen that an electrode element embodying the invention provides means for assembling the electrodes, filaments and connections. in a unitary structure which may be mounted on a base such as 15 and inserted and sealed in the arc chamber. Since all of these elements are supported by a common means, only one or more supports such as 18 are required and the entire assemblage is mounted at one end only of the arc chamber. Therefore only one sealing operation is required for the ultra-violet producing element, the bulb 11 being formed in the usual manner and the stem 15 being sealedtherein in accordance with the usual lamp-making practice. Moreover, this arrangement eliminates the precision heretofore required in mounting the electrodes in the arc chamber, since the electrodes are secured rigidly in definitely spaced relation. The passages within the element 19 constitute a convenient and easy way of mounting the heating filaments for the electrodes and at the same time afford means for enclosing the hot wires and filaments.

; While only one embodiment of the invention has been described and illustrated in the drawing, it will be understood that the invention is capable of a variety of mechanical expressions many of which will now occur to those skilled in the art and that changes maybe made in the form, details of construction and arrangement of the parts without departing from the spirit of the invention. It will also be understood that the use of the electrode element is not restricted to lamps of the type described above. Thus the ultra-violet producing element described may be used alone and apart from the incandescent filament and outer bulb, and the electrode element may further be employed in any are lamp for which it is suitable. Reference is therefore to be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. An electrode element for use in electric arc lamps comprising a single member of insulating material having a plurality of passages therein, spaced electrodes carried by said member, and wires enclosed in said passages. for supplying current to said electrodes.

2. An electrode element for use in electric arc lamps comprising a single substantially cylindrical member of insulating material having passages therein, a pair of electrode sleeves spaced axially on said member, filaments in said passages for heating said electrode sleeves, means for energizing said filaments, and means connecting said filaments and electrodes whereby the potential drop through said filaments is impressed across said electrodes.

3. An electrode element for use'in electric arc lamps comprising a member of insulating material, means for supporting said member, a pair of spaced electrode sleeves on said member, heating filaments for said sleeves housed within said member and connected in series, wires connecting the ends of said series circuit with the respective electrodes whereby the potential drop through said filaments is impressed across the electrodes'and a resistance connected in one of said wires and housed within said member.

4. An electrode element for electric arc lamps comprising asubstantially cylindrical member 'of insulating material, electrode means on opposite ends of said member, means for supporting said member from one end thereof, and means within said member for supplying current to said electrode means.

5. An electrode element for electric arc lampscomprising a member of insulating material having passages therein, metal electrodes onopin said passages adjacent said electrodes, and connections from said filaments to said electrodes. I

6. An electrode element for electric arcs comprising a member of insulating material having passages therein, electrodes at opposite ends of said member comprising ,metallic elements coated with oxide having electronic emission,- heating filaments in said passages adjacent said electrode element therein comprising a substantially cylindrical member of insulating material having passages therein, electrodes on opposite ends of said member, heating filaments in said Passages adjacent said electrodes, and connections from said filaments to said electrodes,

means for supporting said element in said bulb, terminals external to said bulb, and a pair of leads from said filaments to said terminals.

9. An electrode element foruse in electric arc lamps comprising a single substantially cylindri- 1 15 posite ends of said member, heating filaments cal member of insulating material, a pair of electrodes carried by and spaced axially on said member, a pair of leads for supplying current to said electrodes, and a resistance heating element electrically connected between said electrodes, said resistance element and at least one of said leads being housed within the insulating member.

10. An electrode element for use in electric arc lamps comprising a member of insulating material, a pair of electrodes carried by and spaced on said member, a coating of electron-emissive oxide also carried by said member, a pair of leads for supplying current to said electrodes, and a resistance element electrically connected between said electrodes, said resistance element being housed within the insulating member and adapted to heat said oxide coating.

12. An electrode element for use in electric arc lamps comprising a member of insulating material having a passage therein, metallic electrodes carried by said member adjacent the opposite ends thereof, a sleeve of electron-emissive oxide also carried by said member, a pair of leads for supplying current to said electrodes, and a resistance element-electrically connected between said electrodes, said resistance element being housed within said passage and adapted to heat said sleeve.

GEORGE SPERTI. 

